1. Field of the Invention
The invention relates to improvements in or to baker's yeast, these improvements consisting both in novel yeasts and in novel applications of already described yeasts and improved methods of preparation, it being recalled that said baker's yeasts can be in the form of fresh yeast with about 28 to 35% of dry matter or in the form of active dry yeast with more than 92% of dry matter.
2. Description of the Prior Art
It is known that bread-making yeasts are strongly inhibited by acetic acid and mixtures of acetic acid and lactic acid which are added or developed naturally by lactic bacteria within the scheme of certain bread-making operations such as sour leavened breads and rye breads as well as acid breads generally. It is known on the other hand, that bread-making yeasts are inhibited by mold inhibitors which are added to the dough on kneading, to increase the preservation of the bread. These mold inhibitors are, besides the acetic acid already mentioned as well as its salts, propionic and sorbic acids as well as their sodium and calcium salts.
Inhibition of the bread-making yeast leads to alteration of its fermentative power, that is to say, a loss in fermenting power which can exceed 66% according to tests carried out with the zymotachygraph, this alteration having the result either of the necessity to increase to very considerable proportions the amounts of yeast necessary, or the obtaining of breads which are little developed.
The degree of inhibition of the yeast depends on the concentration of the inhibitor organic substances and on the pH which intervenes in the percentage of dissociation of these substances. In fact, it would seem that it is essentially the organic acid in its undissociated form which has the inhibitor action.
This problem of inhibition of bread-making fermentation by acetic acid and mold inhibitors present in the dough concerns a part of bread-making in numerous countries.
It is an object of the invention to overcome these drawbacks.